Talk:ACPI Wakeup

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Revision as of 14:42, 10 October 2009 by Kurtkimber(talk | contribs)(→‎I would like to split ACPI Wakeup into two different pages: Deleted this section since it was, IMO, no longer relevant. Also added the section heading "Wake on USB?")

It works on 32 bit as well. If you miss /proc/acpi/alarm then it seems that this dissapears if you run smp.

Does anyone have experience with the Via EPIA boards? I'm not able to get it working and thus still use nvram-wakeup...

How do I use ACPI wakeups with MythWelcome? The instructions for it are all for using it with nvram-wakeup. --Turpie 11:09, 29 December 2006 (UTC)

http://svn.mythtv.org/trac/ticket/2838 Looks like capability for ACPI with MythWelcome is coming. Hopefully we'll see an update to the WIKI once 0.21 comes out or sooner if someone with svn version gets ambitious.

Contents

2.6.22 Kernels

I just updated my fedora 7 kernel and apparently the 2.6.22 linux kernel removes the /proc/acpi/alarm feature, see http://lkml.org/lkml/2007/6/22/320 does anyone know the new method for these new kernels? --Vossman 06:18, 23 July 2007 (UTC)

There is no documentation, only some hidden description in the git commit that introduced this feature. So I wrote some short documentation, but it isn't included in the source tree yet, AFAIK.

I am having the same issue as this guy here [1] I have no trouble getting the value into the /sys/class/rtc/rtc0/wakealarm that is all fine and dandy. But my machine does not wake up when I set this value. I use Fedora 7 and /proc/acpi/alarm worked great before. I am thinking of reporting this to bugzilla.kernel.org and bugzilla.redhat.com if other people are experiencing this post a comment. --Vossman 16:01, 8 September 2007 (UTC)

I finally got wakeup working with the 2.6.26 kernel after applying the patch found here. Steps to test:

Fedora Core 6 kernel 2.6.22.5 vs kernel 2.6.22.9

I have a backend running FC6 (kernel 2.6.22.5-49.fc6) that shuts down and wakes up just fine using the script mentioned in the article. However, after upgrading to kernel 2.6.22.9-61.fc6, it no longer works. I figured out (thanks to the comment in the article) that a new wakeup mechanism is in place for the new kernel, namely /sys/class/misc/rtc/power/wakeup. I tried using that, but all I get when I try to echo anything into it (as root) is "invalid argument". Even resetting fails (echo 0 > /sys/class/misc/rtc/power/wakeup). As of writing, this article is the *only* place that mentions this path in google's index. I've reverted to the 2.6.22.5 kernel which still works great, using mythtv-0.20.2-167.fc6.
Judaz 19:16, 6 November 2007 (UTC)

This is in response to Judaz's post above. /sys/class/rtc/rtc0/wakealarm has NOT been moved to /sys/class/misc/rtc/power/wakeup. The documentation provided with the kernel source explains that the wakeup file is a way to query/set whether a device in the system can wakeup. Here's an excerpt from the 2.6.23.12 kernel source documentation that describes the power/wakeup files in sysfs (found in Documentation/power/devices.txt):

/sys/devices/.../power/wakeup files
-----------------------------------
All devices in the driver model have two flags to control handling of
wakeup events, which are hardware signals that can force the device and/or
system out of a low power state. These are initialized by bus or device
driver code using device_init_wakeup(dev,can_wakeup).
The "can_wakeup" flag just records whether the device (and its driver) can
physically support wakeup events. When that flag is clear, the sysfs
"wakeup" file is empty, and device_may_wakeup() returns false.
For devices that can issue wakeup events, a separate flag controls whether
that device should try to use its wakeup mechanism. The initial value of
device_may_wakeup() will be true, so that the device's "wakeup" file holds
the value "enabled". Userspace can change that to "disabled" so that
device_may_wakeup() returns false; or change it back to "enabled" (so that
it returns true again).

The wakealarm file should still reside in /sys/class/rtc/rtcN. If that directory does not exist on your system, it means the kernel was compiled without support for /sys/class/rtc/rtcN. If you're building your own kernel, you can enable it in "make menuconfig" via the following:

Why is the argument $2, which is seconds since epoch, converted into seconds since epoch? I think that part can be scratched. Just echo $2 > /sys/class/rtc/rtc0/wakealarm should do fine (at least it does for me)

Disable or Enable in BIOS?

On most motherboards, you need to disable it in BIOS, because you want to program the RTC from the OS. There used to be notes about almost all motherboards needing to disable it. But if your motherboard is an exception, you should probably add a note to the wiki about some motherboards needing it enabled. BTW, have you tried disabling it to make sure you need it enabled? --Per Olofsson 20:01, 26 May 2008 (UTC)